Also most all interest only loans are a 30 yr amortized loan with a 10 yr I/O period. At 6% this payment is 3410 not 3000. Second this would be a jumbo loan so that 6% rate would not happen, it would be more along the lines of 6.5% so now we are at 3694.

You’re using current rates, but 2003 was a bit different. National average rates for 5/1 IO ARMs were around 4.5%, jumbo or not. 682000 * 0.045 / 12 = $2557. Less if you have a down payment. Total housing payments (mortgage/insurance/etc.) on the order of $3600/month.

Lots of engineers, or similarly salaried professionals, perhaps even a few dual income types, pulling in a minimum of 100k per household.

In 2005, median household income of 92024 was around $77k.